The Bombay Stock Exchange benchmark Sensex fell by about 60 points to trade below 17k level in opening trade on Wednesday after witnessing three-session winning streak. The Sensex slipped by 59.85 points to 16,990 points in opening trade. It had gained about 355 points in the past three sessions. The wide-based National Stock Exchange index Nifty also drifted by 17 points to 5,044.